/* eslint-disable */
import { saveAs } from 'file-saver'
import XLSX from 'xlsx'

function generateArray (table) {
    var out = []
    var rows = table.querySelectorAll('tr')
    var ranges = []
    for (var R = 0;R < rows.length;++R) {
        var outRow = []
        var row = rows[R]
        var columns = row.querySelectorAll('td')
        for (var C = 0;C < columns.length;++C) {
            var cell = columns[C]
            var colspan = cell.getAttribute('colspan')
            var rowspan = cell.getAttribute('rowspan')
            var cellValue = cell.innerText
            if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue

            //Skip ranges
            ranges.forEach(function (range) {
                if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
                    for (var i = 0;i <= range.e.c - range.s.c;++i) outRow.push(null)
                }
            })

            //Handle Row Span
            if (rowspan || colspan) {
                rowspan = rowspan || 1
                colspan = colspan || 1
                ranges.push({
                    s: {
                        r: R,
                        c: outRow.length
                    },
                    e: {
                        r: R + rowspan - 1,
                        c: outRow.length + colspan - 1
                    }
                })
            };

            //Handle Value
            outRow.push(cellValue !== "" ? cellValue : null)

            //Handle Colspan
            if (colspan)
                for (var k = 0;k < colspan - 1;++k) outRow.push(null)
        }
        out.push(outRow)
    }
    return [out, ranges]
};

function datenum (v, date1904) {
    if (date1904) v += 1462
    var epoch = Date.parse(v)
    return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000)
}

function sheet_from_array_of_arrays (data, opts) {
    var ws = {}
    var range = {
        s: {
            c: 10000000,
            r: 10000000
        },
        e: {
            c: 0,
            r: 0
        }
    }
    for (var R = 0;R != data.length;++R) {
        for (var C = 0;C != data[R].length;++C) {
            if (range.s.r > R) range.s.r = R
            if (range.s.c > C) range.s.c = C
            if (range.e.r < R) range.e.r = R
            if (range.e.c < C) range.e.c = C
            var cell = {
                v: data[R][C]
            }
            if (cell.v == null) continue
            var cell_ref = XLSX.utils.encode_cell({
                c: C,
                r: R
            })

            if (typeof cell.v === 'number') cell.t = 'n'
            else if (typeof cell.v === 'boolean') cell.t = 'b'
            else if (cell.v instanceof Date) {
                cell.t = 'n'
                cell.z = XLSX.SSF._table[14]
                cell.v = datenum(cell.v)
            } else cell.t = 's'

            ws[cell_ref] = cell
        }
    }
    if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range)
    return ws
}

function Workbook () {
    if (!(this instanceof Workbook)) return new Workbook()
    this.SheetNames = []
    this.Sheets = {}
}

function s2ab (s) {
    var buf = new ArrayBuffer(s.length)
    var view = new Uint8Array(buf)
    for (var i = 0;i != s.length;++i) view[i] = s.charCodeAt(i) & 0xFF
    return buf
}

export function export_table_to_excel (id) {
    var theTable = document.getElementById(id)
    var oo = generateArray(theTable)
    var ranges = oo[1]

    /* original data */
    var data = oo[0]
    var ws_name = "SheetJS"

    var wb = new Workbook(),
        ws = sheet_from_array_of_arrays(data)

    /* add ranges to worksheet */
    // ws['!cols'] = ['apple', 'banan'];
    ws['!merges'] = ranges

    /* add worksheet to workbook */
    wb.SheetNames.push(ws_name)
    wb.Sheets[ws_name] = ws

    var wbout = XLSX.write(wb, {
        bookType: 'xlsx',
        bookSST: false,
        type: 'binary'
    })

    saveAs(new Blob([s2ab(wbout)], {
        type: "application/octet-stream"
    }), "test.xlsx")
}

export function export_json_to_excel ({
    multiHeader = [],
    header,
    data,
    filename,
    merges = [],
    autoWidth = true,
    bookType = 'xlsx'
} = {}) {
    /* original data */
    filename = filename || 'excel-list'
    data = [...data]
    data.unshift(header)

    for (let i = multiHeader.length - 1;i > -1;i--) {
        data.unshift(multiHeader[i])
    }

    var ws_name = "SheetJS"
    var wb = new Workbook(),
        ws = sheet_from_array_of_arrays(data)

    if (merges.length > 0) {
        if (!ws['!merges']) ws['!merges'] = []
        merges.forEach(item => {
            ws['!merges'].push(XLSX.utils.decode_range(item))
        })
    }

    if (autoWidth) {
        /*设置worksheet每列的最大宽度*/
        const colWidth = data.map(row => row.map(val => {
            /*先判断是否为null/undefined*/
            if (val == null) {
                return {
                    'wch': 10
                }
            }
            /*再判断是否为中文*/
            else if (val.toString().charCodeAt(0) > 255) {
                return {
                    'wch': val.toString().length * 2
                }
            } else {
                return {
                    'wch': val.toString().length
                }
            }
        }))
        /*以第一行为初始值*/
        let result = colWidth[0]
        for (let i = 1;i < colWidth.length;i++) {
            for (let j = 0;j < colWidth[i].length;j++) {
                if (result[j]['wch'] < colWidth[i][j]['wch']) {
                    result[j]['wch'] = colWidth[i][j]['wch']
                }
            }
        }
        ws['!cols'] = result
    }

    /* add worksheet to workbook */
    wb.SheetNames.push(ws_name)
    wb.Sheets[ws_name] = ws

    var wbout = XLSX.write(wb, {
        bookType: bookType,
        bookSST: false,
        type: 'binary'
    })
    saveAs(new Blob([s2ab(wbout)], {
        type: "application/octet-stream"
    }), `${filename}.${bookType}`)
}
